1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #if defined(LIBC_SCCS) && !defined(lint) 36 static char sccsid[] = "@(#)setvbuf.c 8.2 (Berkeley) 11/16/93"; 37 #endif /* LIBC_SCCS and not lint */ 38 #include <sys/cdefs.h> 39 #include "namespace.h" 40 #include <limits.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include "un-namespace.h" 44 #include "local.h" 45 #include "libc_private.h" 46 47 /* 48 * Set one of the three kinds of buffering, optionally including 49 * a buffer. 50 */ 51 int 52 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size) 53 { 54 int ret, flags; 55 size_t iosize; 56 int ttyflag; 57 58 /* 59 * Verify arguments. The `int' limit on `size' is due to this 60 * particular implementation. Note, buf and size are ignored 61 * when setting _IONBF. 62 */ 63 if (mode != _IONBF) 64 if ((mode != _IOFBF && mode != _IOLBF) || size > INT_MAX) 65 return (EOF); 66 67 FLOCKFILE_CANCELSAFE(fp); 68 /* 69 * Write current buffer, if any. Discard unread input (including 70 * ungetc data), cancel line buffering, and free old buffer if 71 * malloc()ed. We also clear any eof condition, as if this were 72 * a seek. 73 */ 74 ret = 0; 75 (void)__sflush(fp); 76 if (HASUB(fp)) 77 FREEUB(fp); 78 fp->_r = fp->_lbfsize = 0; 79 flags = fp->_flags; 80 if (flags & __SMBF) 81 free((void *)fp->_bf._base); 82 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF); 83 84 /* If setting unbuffered mode, skip all the hard work. */ 85 if (mode == _IONBF) 86 goto nbf; 87 88 /* 89 * Find optimal I/O size for seek optimization. This also returns 90 * a `tty flag' to suggest that we check isatty(fd), but we do not 91 * care since our caller told us how to buffer. 92 */ 93 flags |= __swhatbuf(fp, &iosize, &ttyflag); 94 if (size == 0) { 95 buf = NULL; /* force local allocation */ 96 size = iosize; 97 } 98 99 /* Allocate buffer if needed. */ 100 if (buf == NULL) { 101 if ((buf = malloc(size)) == NULL) { 102 /* 103 * Unable to honor user's request. We will return 104 * failure, but try again with file system size. 105 */ 106 ret = EOF; 107 if (size != iosize) { 108 size = iosize; 109 buf = malloc(size); 110 } 111 } 112 if (buf == NULL) { 113 /* No luck; switch to unbuffered I/O. */ 114 nbf: 115 fp->_flags = flags | __SNBF; 116 fp->_w = 0; 117 fp->_bf._base = fp->_p = fp->_nbuf; 118 fp->_bf._size = 1; 119 goto end; 120 } 121 flags |= __SMBF; 122 } 123 124 /* 125 * Kill any seek optimization if the buffer is not the 126 * right size. 127 * 128 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? 129 */ 130 if (size != iosize) 131 flags |= __SNPT; 132 133 /* 134 * Fix up the FILE fields, and set __cleanup for output flush on 135 * exit (since we are buffered in some way). 136 */ 137 if (mode == _IOLBF) 138 flags |= __SLBF; 139 fp->_flags = flags; 140 fp->_bf._base = fp->_p = (unsigned char *)buf; 141 fp->_bf._size = size; 142 /* fp->_lbfsize is still 0 */ 143 if (flags & __SWR) { 144 /* 145 * Begin or continue writing: see __swsetup(). Note 146 * that __SNBF is impossible (it was handled earlier). 147 */ 148 if (flags & __SLBF) { 149 fp->_w = 0; 150 fp->_lbfsize = -fp->_bf._size; 151 } else 152 fp->_w = size; 153 } else { 154 /* begin/continue reading, or stay in intermediate state */ 155 fp->_w = 0; 156 } 157 __cleanup = _cleanup; 158 159 end: 160 FUNLOCKFILE_CANCELSAFE(); 161 return (ret); 162 } 163